Polycyclic aromatic hydrocarbons (PAHs) are well-known environmental contaminants, but the observed toxicity and mutagenicity of complex environmental samples cannot be explained solely by the activity of known parent PAHs. PAH derivatives, such as NPAHs, are receiving increasing attention as potential important toxicants. However, there are many NPAHs, termed 'novel', which are predicted to be in the environment, are not yet commercially available, and have uncharacterized toxicity. The objective of this proposal is to determine if the novel NPAHs are present in the environment, and to investigate their developmental toxicity in a high throughput in vivo system. The overall hypothesis is that novel NPAHs are present in the environment and that they will generate adverse biological responses in the embryonic zebrafish (Danio rerio) model in a structure-dependent manner. This hypothesis will be tested by completing the following Specific Aims: Aim 1: Identify and measure novel NPAHs in the environment Aim 2: Define the bioactivity of NPAHs in the high throughput embryonic zebrafish model Aim 3: Determine metabolites produced from in vivo metabolism of NPAHs in the embryonic zebrafish model These aims will be completed by using gas chromatography mass spectrometry (GC/MS) for the detection of novel NPAHs in the environment, as well as toxicity screening and metabolism studies using the zebrafish model. In order to collect data with the highest human relevance, a transgenic zebrafish model will be utilized which expresses nitroreductase (an enzyme found in humans, but not zebrafish, which is responsible for the reduction of nitro functional groups). These studies will advance the field of environmental health by providing new data streams to allow for a more accurate assessment of potential health impacts resulting from environmental NPAH exposures, and will provide impetus to study some of the identified compounds in other systems.